This invention generally relates to the lining of passageways and pipelines. It is well known in the art to line an existing underground pipe or passageway by introducing a flexible tubular liner into the pipe at one end. Typically, the liner includes a portion that is impermeable to fluid and a portion that includes a curable resin. The liner is placed into one end of the pipe and anchored at that end. The liner then progresses via an eversion process throughout the interior of the pipe or is pulled in by a winch. The liner is, therefore, turned inside out as it makes its way through the pipe. The liner can also be coated on both sides of the resin impregnated fabric.
The means to evert the liner is typically fluid pressure produced by partially filling the everted liner in the passageway with a liquid. Curing of the resin is the chemical reaction which is accelerated by an elevated temperature. When liquid is used, the resin is cured by supplying the liquid at a controlled temperature which is sufficient to set the resin. The fluid pressure of the heated liquid is maintained in the pipe until the resin has properly cured. After curing, the existing pipe is sealed by the new liner which will have repaired cracks or other damage to the original pipe or previous liner. Typically, the lined pipe is equal to or greater in strength that the original pipe.
One of the deficiencies in the prior art associated with cured in place pipes is that the cure process requires refrigeration of the liner prior to installation to extend the pot life of the resin so that the resin does not prematurely set prior to installation in the pipe. Additionally, the resins compatible with the methods of the prior art may necessitate a resin possessing a long cure time. As such, the prior art methods consume large amounts of resources and energy in the refrigeration of the resin as well as the curing of the resin through water or by the use of a combination of steam and air and sometimes by the use of ultraviolet light. Furthermore, monitoring the progress of the curing process is difficult, which leads to inefficient use of materials and labor. Additionally, under-cured or incomplete cure of the resin can lead to lifts or compromised physical properties of the resin and liner.
It is therefore an object of the present invention to provide a method which cures the liner by means of using microwave energy to deposit thermal energy into the resin to speed up the curing process.
It is another object of the present invention to provide a method for monitoring the temperature of the resin in the liner so as to monitor the cure process along the entire periphery and length of the pipe liner.
It is another object of the present invention to provide a liner fabric which cures in an accelerated manner due to the microwave sensitivity of the fabric.
It is yet another object of the present invention to add a shielding layer to the fabric tube to prevent the microwave energy from escaping the tube during the cure process where the pipe being repaired is non-metallic or covered with dirt or other shielding materials.
It is yet another object of the present invention to provide a method for lining pipes which does not necessarily require refrigeration of the liner prior to installation.